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Summary:ASTERISK-14838: udptl.conf parameter T38FaxUdpEC is not working correctly if set to t38UDPRedundancy
Reporter:Bastian Schern (schern)Labels:
Date Opened:2009-09-15 12:55:53Date Closed:2011-06-07 14:00:32
Priority:MajorRegression?No
Status:Closed/CompleteComponents:Channels/chan_sip/T.38
Versions:Frequency of
Occurrence
Related
Issues:
Environment:Attachments:( 0) T38UDPFEC_ERROR_01.log.gz
( 1) T38UDPFEC_ERROR_02.log.gz
Description:If I set the parameter T38FaxUdpEC = t38UDPRedundancy in udptl.conf the SDP part of the T.38 re-INVITE from Asterisk to the carrier always contains the wrong EC method:
[...]
a=T38FaxMaxDatagram:140
a=T38FaxUdpEC:t38UDPFEC
[...]

Correct would be a=T38FaxUdpEC:t38UDPRedundancy.

In Asterisk v1.6.0.6 and 1.4.x the EC method is set correctly to the value of the udptl.conf.

****** STEPS TO REPRODUCE ******

FAX ATA ---SIP+T.38---> Asterisk ---SIP+T.38---> Carrier

****** ADDITIONAL INFORMATION ******

My udptl.conf:
[general]
udptlstart=4000
udptlend=4999
;udptlchecksums=no
T38FaxUdpEC = t38UDPRedundancy
T38FaxMaxDatagram = 1400
udptlfecentries = 3
udptlfecspan = 3
use_even_ports = no
Comments:By: Kevin P. Fleming (kpfleming) 2009-09-15 13:42:35

Your log is nearly impossible to follow; please follow the bug posting guidelines and post *only* a capture of the log from Asterisk itself showing the packets it received and sent, using 'sip set debug on' to see how Asterisk parsed and processed them.
By: Bastian Schern (schern) 2009-09-15 17:04:04

Sorry for bad log. I created a new directly with Asterisk (T38UDPFEC_ERROR_02.log.gz):

The bad EC method you can see at line 485.

The IPs in the log are used by the following devices:
1.2.3.150 = Asterisk IP
172.30.48.24 = ATA Device (internal IP)
1.2.3.21 = ATA Device (external IP)
1.2.3.160 = CUSTOMER PROXY
1.2.3.154 = Carrier Proxy #1

Not so important IPs:
1.2.3.70 = Carrier Proxy #2
1.2.3.81 = Carrier Proxy #3
1.2.3.11 = Carrier Gateway
By: Kevin P. Fleming (kpfleming) 2009-10-01 11:02:14

In Asterisk 1.6.1.6, control over which method of UDPTL redundancy is offered to a SIP endpoint is actually done from sip.conf, not udptl.conf. In fact, the udptl.conf setting for redundancy mode no longer has any useful effect. Please see the sip.conf.sample included with Asterisk 1.6.1.6 to learn how to configure this setting for your peers. Thanks.